Three primary technologies are currently used for seawater desalination: Multi Stage Flash Distillation (MSF); Multi Effect Desalination (MED); and Reverse Osmosis desalination (RO). A newer technology, Capacitive Deionization Technology (CDT), was developed in the 1990s, but has not been implemented commercially. MSF and MED technologies use thermal processes and depend on the availability of low cost waste heat for economic operation. If waste heat is not available, the energy consumption of these approaches is very high; typically too high for practical commercial applications. RO, in contrast, operates at ambient temperatures, but requires high pressure to push the water through the membranes. RO is therefore energy consumptive. In addition, the membranes used in RO processes need to be cleaned on a regular basis and they have a limited lifetime; therefore, the membranes must be replaced at high cost after limited operation.
Historical attempts to reduce capacitive deionization phenomenon to a practical CDT technology have not been successful, due to a lack of appropriate construction materials and suitable designs for functional devices. Recently, a novel electrode material, carbon aero-gel, which has favorable performance characteristics, has been discovered. It is currently believed that combining this aero-gel material with the macroscopic designs of a deionization cell that would be applicable in a commercial setting likely would cause inefficiently slow diffusion of salt away from the electrodes of the apparatus during discharge cycles. Such slow diffusion provides only a small fraction of deionized fluid from the impure fluid supply. A need therefore still exists for devices that are capable of providing purified fluids, particularly water, while minimizing the energy requirements needed for operation.